I grow on a much smaller scale so I don't know if this will be helpful to you, but just in case you can adapt something:

I mostly use wire animal fencing for trellises. In one area I have a few rows with discontinuous trellising, so 1 fence panel, then a 2-3' gap, then another fence panel. The vines rarely try to stretch horizontally within the same row, so they all stay separate with little minding on my part. In the area with a continuous line of trellis I plant different things between the different bean types, like scarlet runners, lima beans, hyacinth beans, dwarf melons, morning glories, squash; anything that can climb a bit (or be trained) and isn't too dainty. Thin-stemmed or late-season things like decorative cucumbers, "mouse melon" cucumbers, and cypress vine tend to get overshadowed and lost.

I have often used those plastic 'clips' that are on bread bags and potato sacks. Not the plastic-coated wire twist-ties, rather, the flat - square or rectangular - clips. You can simply use a marker to write a designation or the variety name and 'clip' it around a leaf or the stem, or hang it from a petiole with a twist-tie, and you're done. You can also break, or cut off half the 'clip' and it forms a hook. Be careful if you do make the 'hook', it can blow off in the wind.

You don't even have to hang it on or around the plant stem, I also use them to mark squash flowers after I hand pollinate. I simply lay it on the ground next to the pollinated flower. Easy - peazy.

As a rule, since I am usually saving seed, I try to avoid planting different bean varieties adjacent to each other. However, I have used the method used by Sea_kangaroo in the past... interplanting different bean species (such as runner beans, limas, or yardlongs) as dividers between different beans. A single plant of scarlet runner beans between each variety would make a good divider, although some of the more aggressive beans might cross over.

I use stakes to mark rows of anything that is direct seeded, so that I can watch for germination... and to keep me from double-planting in a row that was already seeded with something else (says one who has done that) ;-) A map for each plot shows what is planted where.

Some great ideas here. Thanks!